OG12 #78 关于pronoun的antecedent的问题

kwonku

Fossils of the arm of a sloth found in Puerto Rico in
1991, and dated at 34 million years old, made it the
earliest known mammal of the Greater Antilles Islands.

这里OG有一则解答：
Because sloth is the object of a preposition and not the subject of the sentence，there is no reasonable antecedent for the pronoun it

是不是因为sloth相当于是用来修饰arm的，所以，根据Manhattan的内容，这里的sloth不能算作真正意义上的noun，所以no reasonable？

谢谢大家啦！！

sisichen666

你理解的差不多吧，简单地说就是代词的指代：不能指代介宾结构中的N